platinum-iridium

Standard, against which all others of
the same category are measured. Usage: silly. The notion is that
one of whatever it is has actually been cast in platinum-iridium
alloy and placed in the vault beside the Standard Kilogram at the
International Bureau of Weights and Measures near Paris. (From
1889 to 1960, the meter was defined to be the distance between two
scratches in a platinum-iridium bar kept in that same vault --
this replaced an earlier definition as 10^(-7) times the
distance between the North Pole and the Equator along a meridian
through Paris; unfortunately, this had been based on an inexact
value of the circumference of the Earth. From 1960 to 1984 it was
defined to be 1650763.73 wavelengths of the orange-red line of
krypton-86 propagating in a vacuum. It is now defined as the
length of the path traveled by light in a vacuum in the time
interval of 1/299,792,458 of a second. The kilogram is now the
only unit of measure officially defined in terms of a unique
artifact.) "This garbage-collection algorithm has been tested
against the platinum-iridium cons cell in Paris." Compare
golden.